Unbalance compensated fluid cushion devices



May 12; 1970' J. D. LlVES-AY UNBALANCE COMPENSATED FLUID CUSHION DEVICES Filed June 20, 1968 3 Sheets-Sheet 1 I I N VENTOR. aflfil esay ATTORNEY May 12, 1970 J. D. LIVESAY 3,511,330

UNBALANCE COMPENSATEQ FLUID CUSHION DEVICES Filed June 20, 1968 v s Sheets-Sheet 2 Ag W 451 INVEINTOR.

J17. [ix/way ATTORNEY y 12, 1970 I J. D. LIVESAY 3,511,330

- UNBALANCE COMPENSATED FLUID CUSHION DEVICES Filed June 20, 1968 s Sheets-Sheet 5 I N VENTOR.

J17. [fl/way Q! M ATTORNEY United States Patent M 3,511,330 UNBALANCE COMPENSATED FLUID CUSHION DEVICES J. D. Livesay, Tipp City, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed June 20, 1968, Ser. No. 738,649 Int. Cl. B60v 1/04 U.S. Cl. 180-118 4 Claims ABSTRACT OF THE DISCLOSURE In preferred form, a ground proximate fluid cushion device including a platform, flexible diaphragm means located horizontally beneath the platform defining a plurality of pads for forming distinct and separate fluid cushions beneath the platform, each of the pads including an inflatable cavity formed in part by a depending continuously curved convolution in said diaphragm means progressing from a peripherally attached point on the platform to a narrow annular throttling gap located in close spaced relationship with the ground, the throttling gap zone having a perimetrical shape to form the boundary of a plenum cavity between the diaphragm means and the ground at each pad, and a fluid supply system including automatic flow proportioning valve means for controlling the air supply to each of the plurality of pads for varying the fluid cushions formed by the pads to compensate for unbalanced loads on the platform.

This invention relates to wheelless load supporting devices and more particularly to devices which are supported relative to the ground solely by means of a low pressure free fluid cushion.

Ground proximate fluid supporting devices of the type set forth in United States Pat. No. 3,321,038 to Mackie et al. may have a load support platform that extends through a substantial horizontal planar extent. In such devices it has been found desirable, in certain applications, to form a flexible depending diaphragm component into separate plenum cavity forming pads to produce distinct and separate air cushions acting upwardly on the platform to support it above the underlying ground.

Ground proximate fluid cushion devices having such plural cushion defining pads will tend to resist tipping movements of the platform and resultant load support instability. Nevertheless, in devices of this type when substantial unbalanced loading is placed on the platform periphery, one part of the platform can be forced toward the underlying ground and a commensurate uplifting action can occur on the opposite side of the platform. This tipping action produces instability in the ground proximate fluid cushion device manifested by engagement of the flexible diaphragm on the underlying ground and a reduction in the fluid support pressure in the plenum cavities of the device.

An object of the persent invention is to improve the stability of ground proximate fluid cushion devices of the type including a load carrying platform and a low profile depending flexible diaphragm with plural fluid cushion pads defined by annular depending diaphragm convolutions each continuously curving downwardly from the platform to a lower extremity in close spaced relationship to the underlying ground to define a continuous perimetrical throttling gap that bounds a plenum cavity underlying the diaphragm and located between it and the ground and wherein the convolution cooperates with a second part of the flexible diaphragm to form a plurality of sparate pressurizable chambers each of which has a separate fluid inlet and each of which communicates with 3,511,330 Patented May 12, 1970 a plenum cavity to produce a plurality of separate and distinct fluid cushions beneath the platform by the provision of pressure responsive valving mechanism communicating the separate fluid inlets with a source of fluid pressure including a'pivoted valving element that senses pressure changes within each of the pressurizable cham-v bers produced upon tipping movement of the platform with respect to the underlying ground and that automatically proportions fluid flow from the pressure source through the separate fluid inlets to increase the fluid cushion at a point underlying the part of the platform tipping toward the ground and decrease the fluid cushion underlying the part of the platform being raised from the ground thereby to produce a resultant corrective moment on the platform to compensate for unbalanced loading.

A further object of the present invention is to improve the stability ground proximate fluid cushion devices of the type including a load carrying platform and a plurality of underlying pads each including a flexible diaphragm having a continuously curved depending convolution therein progressively spaced from the platform at a peripherally connected point thereon to a lowermost extremity on the convolution located in close proximate relationship with the underlying ground to define a continuous perimetrical throttling gap about a pressurizable plenum cavity in which an uplifting fluid cushion is formed and which has fluid supplied thereto from an inflatable annular inlet chamber that is in part formed by the depending convolution and an intermediate diaphragm portion connecting the lowermost extremity of the convolution and the platform and having a generally truncated conical cross section shape by the provision of a fluid regulator valve in the inlet to the device which controls the amount of fluid supplied to each pad and when the pressure in one pad becomes greater than the other because of uneven loading or platform tilting the regulator valve has a vane component thereof arranged to close off part of the fluid supply to the pad underlying the lightly loaded part of the platform while directing a greater part of the fluid supply to the overloaded side thereby to produce a corrective uplifting moment on the platform.

To attain the above statetd objectives one working embodiment includes a load supporting platform having two generally ovally shaped air cushions on its underside. Each of the cushions includes a pressurizable cavity and an exhaust plenum bounded by a perimetrical control gap during operation. An inlet to the cushions includes a cylindrical valve housing in which is located a spring biased vane element normally centered to evenly divide inlet flow to the air cushions. When the platform is tipped 'by an unbalanced load, the pressure in one or the other of the air cushion cavities is increased and the vane element pivots about a support axis against the centering spring force to divert more inlet flow to the air cushion with the increased pressure. This produces a platform stabilizing movement to counteract the unbalanced load.

These and other objects will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings in which:

FIG. 1 is a view in front elevation of a refrigerator cabinet including the present invention;

FIG. 2 is an enlarged view in horizontal section taken along the line 22 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a view in vertical section taken along the line 33 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a fragmentary view in vertical section taken along the line 4-4 of FIG. 2 looking in the direction of the arrow;

FIG. 5 is an enlarged fragmentary top elevational view of the numbered region 5 in FIG. 2 showing the top of a valve mechanism in the present invention;

FIG. 6 is a vertical sectional view taken along the line 6-6 of FIG. 5 looking in the direction of the arrows;

FIG. 7 is a view in horizontal section taken along line 7-7 of FIG. 6 showing a vane component of the regulator valve in a centered position;

FIG. 8 is a view in horizontal section taken along line 88 of FIG. 6 looking in the direction of the arrows;

FIG. 9 is an enlarged view in perspective of a gasket retainer strip in the present invention;

FIG. 10 is a view in horizontal section taken along the line 1010 of FIG. 6 looking in the direction of the arrows;

FIG. 11 is a view like FIG. 8 showing the vane part of the valve in a first fluid flow controlling position;

FIG. 12 is a view like FIGS. 8 and 11 showing the vane component in a second fluid flow controlling position;

FIG. 13 is a view in top elevation showing another embodiment of the invention;

FIG. 14 is a view in front elevation of the embodiment of FIG. 13;

FIG. 15 is an enlarged top elevational view showing an air regulator valve of the embodiment in FIGS. 13 and 14;

FIG. 16 is a view in vertical section taken along the line 1616 of FIG. 15 looking in the direction of the arrows;

FIG. 17 is a view in vertical section taken along the line 17-17 of FIG. 15 looking in the direction of the arrows; and

FIG. 18 is an enlarged view in horizontal section taken along the line 1818 of FIG. 16.

Referring now more particularly to the drawings, in FIG. 1 a refrigerator 20 is illustrated including a base 22 having an adjustable screw 24 at each corner thereof for leveling the base 22 with respect to ground support. The adjustable leveling screws 24 also locate a ground proximate air cushion device 26 in spaced parallel relationship to the underlying ground.

The ground proximate air cushion device 26 more particularly includes a rectangularly formed platform 28 underlying substantially the complete planar extent of the base 22 of the refrigerator and being connected thereto by suitable fastening means such as the interconnecting arrangement set forth in Pat. No. 3,400,780 to Kesling.

The platform 28 is preferably formed of a thin rigid member having an inlet opening 30 therein as best seen in FIG. 6 and in which is located an improved air regulator assembly 32 constructed in accordance with certain principles of the present invention to selectively direct air into first and second generally oval air cushion defining pad assemblies 34, 36 formed by a flexible diaphragm element which is preferably formed of a thin, tough stretch resistant material having a degree of flexibility such as a polyester reaction product of terephthalic acid and ethylene glycol sold under the trademark Mylar by Du Pont Company.

In the illustrated preferred working embodiment of the invention, a flexible diaphragm 38 forms the air cushion defining pad assembly 34. It has a continuously formed peripheral edge 40 hermetrically sealed to the underside of the platform 28 along a generally oval path as seen in FIG. 2 and has a generally downwardly depending con tinously curved convolution 42 connected thereto which extends completely around the oval shape of the pad assembly 34 and includes a lowermost extremity spaced in close spaced relationship to the underlying ground by the leveling screws 28 to define a shallow clearance or throttling gap 44 between the supporting ground for the unit and the ground proximate air cushion device 26 as best seen in FIG. 3.

The convolution 42 is connected to a centrally located intermediate part 46 of the flexible diaphragm 38 which has a generally truncated conical cross section as seen in FIG. 3 and a continuously formed inner periphery defining an elongated connection path 48 having a narrow width and a substantial length as seen in FIG. 2. The depending convolution 42 and the intermediate part of the flexible diaphragm 38 together form a generally oval inlet cavity 50 which has an inlet conduit 52 connected thereto leading from the improved air regulator assembly 32.

When the regulator 32 is connected to a source of pressure, for example the discharge side of a blower in a domestic vacuum cleaner, compressed air will pass through the inlet conduit 52 into the inflatable inlet chamber 50 causing the diaphragm 38 to be inflated into the shape shown in FIG. 3 wherein the convolution 42 will depend downwardly from the platform 28 along a continuously curved configuration to its lowermost extremity at the throttling gap 44 and the intermediate portion 46 of the diaphragm will be tensioned between its connection point at the inner peripheral path 48 to the convolution 42 to assume the truncated conical shape seen in FIG. 3.

The diaphragm 38 includes a plurality of spaced apart connecting openings 54 on the underside thereof on opposite points of the inner peripheral path 48 as seen in FIGS. 2 and 3 to direct pressurized air from the inlet chamber 50 into a space or plenum cavity 56 formed beneath the platform 28 and surrounded by a perimetrical boundary defined by the throttling gap or clearance 44. The pressurized air introduced into the cavity 56 functions to produce an air cushion supporting the diaphragm 38 and the platform 28 with respect to the underlying ground and during the operation of the device air flow into the inflatable inlet cavity 50 and plenum cavity 56 will continuously escape under the control of throttling gap 44 to maintain pressurization of the inlet chamber 50 and plenum cavity 56 by maintaining an exhaust flow equal to the delivery rate of the inlet flow through the inlet conduit 52.

Underlying the opposite or forward side of the platform 28 from the pad assembly 34 is the pad assembly 36 which includes a flexible diaphragm member 58 with a continuously formed outer peripheral edge 60 thereon hermetrically attached by heat sealing or other suitable means to the underside of the platform 28 along a continuously formed oval line as best seen in FIG. 2. The peripheral edge connects to a downwardly depending continuously curved convolution 62 like the convolution 42 on pad assembly 34. The depending convolution 62 is connected by an intermediate portion 64 of truncated conical shape to an inner peripheral connection path 66 that extends longitudinally of the platform 28 within the peripheral edge 60 of the diaphragm 58 and at a location above the lowest extremity of the convolution 62 as was the case with path 48 on the diaphragm of pad assembly 34.

A plurality of communicating openings 67 in portion 64 communicate an oval inlet chamber 68 between peripheral edge 60 and connection path 66 with an underlying plenum cavity 70 corresponding to the plenum cavity 56 of pad assembly 34. The chamber 68 is in communication with an inlet conduit 72 from the air regulator assembly 32 whereby the diaphragm 58 can be inflated in the same manner as the flexible diaphragm 38 shown in FIG. 3 and to the same configuration whereby the plenum cavity 70 is bound by a perimetrical throttling gap 73 corresponding to the gap 44.

In ground proximate air cushion devices of the aforedescribed type, one characteristic is that the units have a certain amount of inherent stability against grounding out, a condition wherein the flexible diaphragm part of the assembly is forced into direct engagement with the underlying ground thereby to prevent the metered air flow across the throttling gap. Such a condition causes an undesirable, excessive accumulation of inlet air into the assembly with a resultant uneven uplifting action on the pad assembly that can destroy control by the throttling gap. The inherene stability is in part due to the manner in which the continuously curved convolutions 42, 62 around the boundaries of diaphragms 38, 58 are positioned with respect to the underlying ground during variations in loading on the platform. For example, in units of this type is observed that the cross-sectional radius of the continuously curving convolutions of the unit (such as the convolution 42 on pad assembly 34 as seen in FIG. 3) will progressively decrease when the platform descends in parallel relation to the ground as for example, upon being heavily loaded. Also, it is noted that when the platform is lightly loaded it will ascend in parallel relation to the ground causing the continuously curving convolution to have the cross-sectional radius thereof progressively increasing and in both cases a resultant effect is to maintain a diaphragm cross-sectional configuration to hold a predetermined desired clearance height between the lowermost extremity of the convolution and the underlying ground to maintain a controlled, even throttling of fluid from the plenum cavities 56, 70 to atmospheric pressure exteriorly of the perimetrically formed throttling gaps 44, 73.

Under certain operating conditions, however, unbalanced loads can be placed on the platform 28 that will produce a resultant moment thereon which will tip the platform from a desired horizontal relationship with the ground causing a portion of the pad assembly on one side of the platform to be raised from the underlying ground and that on the opposite side to be forced into' nate the desired throttling gap clearance mentioned above.

Under such circumstances the pad assembly that is being compressed toward the underlying ground will have a noticeable pressure increase in its inlet cavity while the unit that is being lightly loaded and tipped above and away from the underlying ground will have a commensurately reduced pressure within the inlet chamber thereof.

In accordance with certain principles of the present invention, the regulator valve assembly 32 includes means responsive to changes in the internal pressures of the respective pressurizable inlet chambers 50, 68 of pad assemblies 34, 36 and operable to direct the greatest amount of the inlet flow under the part of the platform 28 being tipped toward the underlying ground thereby to produce a greater uplifting force against such downward tipping action to compensate for the unbalanced platform loadings.

More particularly, to accomplish this purpose, the improved air regulator valve assembly 3-2, as seen in FIG. 6, includes a 'base 74 connected to the lower end of an upstanding cylindrical valve housing 76 which is located interiorly of a tubular inlet fitting 78 of sheet metal. A lower end 80 of fitting 78 is crimped into interlocking engagement with the platform 28 about the inlet opening 30 therein. The inlet fitting 78 has a supply conduit 82 connected thereto from which pressurized air is directed into the valve housing 76 through an upper open end 84 therein separated into first and second inlet chambers 86, 88 respectively by a vertically directed divider wall 90 that extends throughout the height of the valve housing 76 to have the bottom edge thereof located in sealing engagement with the base member 74.

The divider wall 90' has a rectangularly shaped opening 92 therein in which is located a pressure responsive, movable vane or valving element 94 including a vertically directed, enlarged edge of a generally circular cross section as best seen in FIGS. 8 through inclusive, serving as a hinge portion 96 through which a vertically directed pivot pin 98 is inserted. The pivot pin 98 has the upper end thereof seated within a center segment 97 of the divider wall 90 as seen in FIGS. 6 and 7 and has a lower end thereof supportingly received by the base 74 to maintain the pin 98 in a vertical disposition with respect to the base 74 whereby the vane element 94 will pivot about a predetermined are within the inlet opening 84 between the inlet chambers 86, 88. This moves an outer circumferential arcuate surface segment 99 on vane 94 along the inner circumference of housing 76 in sealing, sliding engagement therewith.

Opposed side faces 100 and 102 on either side of the outer arcuate surface segment 99 extend throughout the. vertical height of vane 94 and are positioned in a centered disposition shown in FIG. 8 by a return spring 104 coiled about the base of the hinge portion 96 as seen in FIG. 5. It includes a first radially outwardly directed segment 106 that extends across the face 100 where its distal end is bent over to engage the bottom of face 100 to exert a clockwise spring biasing action on the vane 94 as viewed in FIG. 8. The return spring 104 also includes a second radially outwardly directed segment 108 that extends in overlying relationship with the vertically directed vane face 102 at the base thereof. It includes a bent distal end that engages the face 102 to exert a biasing action thereagainst equal and opposite to that produced by the spring segment 106 whereby the vane 94 will be maintained in its illustrated centered position.

When the vane 94 is positioned in its centered position, fluid flow through housing inlet 84 will be equally divided between chambers 86, 88. As seen in FIG. 8, chamber 86 is communicated with the inlet conduit 52 by a port 109 in valve housing 76 and by an annular space 110 formed by a generally cup-shaped segment 111 of flexible material integrally formed with diaphragms 38, 58. The segment 111 underlies the valve base 74 and includes an upper peripheral portion 112 continuously formed about the base 74 in heat sealed relationship with the underside of the platform 28. A port 113 in housing 76 communicates chamber 88 through annular space 110 to inlet conduit 72. The cup-shaped segment 111 also supports a pair of diametrically opposed gasket members 114, 115 extending upwardly from segment 111 to the underside of the platform 28 as seen in FIG. 6-.

A retaining strip 116 secured on one side of the cupshaped segment 111 has a pair of spaced apart gasket retaining tabs 117, 118 formed on its bottom end as best seen in FIG. 9. A strip 120 on the diametrically opposite side of segment 111 is identical to strip 116 to retain gasket 115 in place. Each of the gasket retaining strips 116, 120 includes a vertically upwardly directed segment 122 which extends in press-fit relationship between the outer surface of the valve housing 76 and the inside diameter of the inlet fitting 78. The upper end of the gasket retaining strip is bent over and directed radially inwardly at 124 to overlie the upper edge of the valve housing 76 as best seen in FIGS. 5 and 6 to retain the valve housing 76 and its base 74 in a desired air flow controlling relationship within the inlet forming depending'segment 111 joined to the flexible diaphragms 38, 58.

The gaskets 114, 115 and divider wall 90 separate the inlet conduit 52 in the flexible diaphragm from the inlet conduit 72 therein. The housing ports 109, 113 direct an equal amount of the inlet air flow from the conduit 82 through the inlet conduits 5 2, 72 into the respective. inflatable inlet chambers 50, 68 during operative conditions wherein the platform 28 is uniformly loaded and located in a desired spaced parallelism with the underlying ground.

In accordance with certain principles of the present invention, the above-described structure has been found desirable in that it makes the ground proximate, air cushion device 26 more stable when subjected to unbalanced loadings. For example, in the embodiment of the invention in FIGS. 1 through 12, itcan be, subjected to unbalanced loading when the refrigerator 20 is shifted from an at rest position to clean under the base 22 thereof. When the cabinet is shifted, typically, it will be moved on the air cushion formed by the pad assemblies 34, 3-6 across the underlying ground support and, at the same time, it is possible that the platform 28 will be slightly 7 tipped toward the underlying ground in the vicinity of the forwardly located pad assembly 36. When this occurs, the platform 28 is concurrently tipped upwardly of the supporting ground in the vicinity of the rearwardly located pad assembly 34.

When such tipping movement occurs, it is observed that air flow through the throttling gap 73, formed around the perimeter of the plenum cavity 70, becomes more restricted and the pressure within the cavity 70 and annular chamber 68 of the pad assembly 36 will increase. At the same time, there is a tendency for the throttling gap 44, formed around the perimeter of the rearwardly located pad assembly 34, to become greater. This results in a greater escape of air from the plenum cavity 56 of the pad assembly 34. As a result, there is a reduction in air pressure within the plenum cavity 56 and annular inlet chamber 50. The increased pressure in chamber 68 and the concurrently reduced pressure in the chamber 50 produces a pressure differential on the pressure responsive vane element 94 that will act to pivot the vane element 94 about the pin 98 to shift the arcuate peripheral surface 99 thereon from the position shown in FIG. 8 to that shown in FIG. 11. In this position, pressurized air flowing through the inlet conduit 82 into the spaced apart valve housing inlet chambers 86, 88 is free to flow from the chamber 88, thence through the housing port 113 and the inlet conduit 72 into the annular inlet chamber 68 of pad assembly 36 which is overpressurized.

Concurrently, the vane element 94 is maintained by the greater pressure in the inlet chamber 68, which acts on the vane face 102 to overcome the spring biasing action of the radially extended segment 106 of the centering spring 104, so that the radially outwardly arcuate surface segment 99 thereon extends through all but a limited part of the arcuate extent of outlet port 109 in the valve housing 76. Thus, only a small proportion of the inlet air flow through conduit 82 will pass through the valve housing inlet chamber 86, thence through outlet port 109 and inlet conduit 52 into the annular inlet chamber 50 of pad assembly 34. The proportionally reduced air flow into the pad assembly 34 produces a lesser uplifting action on the rearward part of the platform 28 that is being tipped upwardly of ground support. An increased air uplifting elfect is produced by the greater air flow into the pad assembly 36 to oppose the tendency for the unbalanced loading on the platform 28 to tilt it toward ground support. Accordingly, the improved air regulator assembly 32 will effect a desired self-correcting tendency in the air cushion assembly 26.

Under circumstances where the platform 28 is subjected to an unbalanced loading which causes platform 28 to tip in a direction to move the pad assembly 34 closer to the ground support while simultaneously moving the platform 28 to shift the pad assembly 36 away from the ground support, a pressure differential between the inlet chambers 50 and 68 occurs that is reversed from that discussed above. The reverse pressure conditions will act on the vane element 94 to shift it about the pivot pin 98 to locate the arcuate peripheral surface 99 in alignment with the outlet 113 in valve housing 76. As a result, air flow from the conduit 82 is proportionally distributed so that substantially the greatest part of the air flow will be directed into the inlet chamber 50 which has the greater pressure. A reduced flow takes place from inlet chamber 88 through outlet opening 113 where it extends on either side of the vane element 94, as seen in FIG. 12, thence through inlet conduit 72 into the lesser pressurized inlet chamber 68 of pad assembly 36. The air cushion device 26 is accordingly subjected to a stabilizing air flow pattern that will tend to return the platform 26 to a desired space parallelism with ground support.

The embodiment of the invention illustrated in FIGS. 1 through 12 has the following characteristics under actual operating conditions; the stated loads, pressure sources, pad and plate dimensions will vary in accordance with the particular application on which the invention is used. Thus, the following figures are illustrative of only one working embodiment, it being understood that all factors will vary from those stated depending upon the application to which the invention is put.

Item: Rating Load, refrigerator 600 pounds loaded. Pressure source, vacuum Eureka Model 805-B; Filter cleaner Queen Model 33840. Flow rate 25 c.f.m Discharge pressure:

35.5 inches H O At 575 pound load. 20-22 inches H O At 300 pound load. Pads 34, 36 dimensions:

Width 10 /2 inches. Length 25% inches. Thickness .040 inch.

Plate 28 dimensions 22% inchesx 26% inches.

During operating conditions, with a device of the type described above including the air regulator valve 32, it was observed that the air cushion device 26 was more stable in that there was a reduced tendency for the convolutions on the pad assemblies 34, 36 to be grounded into engagement with the supporting floor. Such grounding movement, of course, is a disadvantage in that it will result in destruction of the flow controlling throttling gap, such as gaps 44, 73 in the present invention. Once such gaps are removed during operation, the platform is no longer supported on a frictionless air cushion.

Another embodiment of the invention is illustrated in FIGS. 13 through 18. In FIG. 13, a ground proximate air cushion device is illustrated that includes a rectangularly shaped load supporting platform 132 like platform 28 in the first embodiment. The platform 132 is adapted to be connected to the base of a domestic appliance or for placement beneath a load which is to be transported on a frictionless air cushion produced by the device 130.

Four pad assemblies 134 are located on the underside of the plate 132. Each of the pad assemblies 134 extend through the planar extent of approximately one quarter of the plate 132 as defined by an outer peripheral edge 136 thereon hermetrically secured to the underside of the plate 132. An inner peripheral edge 138 on each assembly 134 is joined in a like manner to the plate 132. The peripheral edges 136, 138 are joined by a convolution in the diaphragm pad assemblies 134 that is curved continuously between the inner and outer peripheral edges 136, 138 to form an inflatable inlet chamber 140, a segment of which is shown in FIG. 16. The convolution between edges 136, 138 includes a lowermost segment that, when the inlet chambers 140 are inflated, will cooperate with underlying ground support to form a throttling gap of the type described in the previous embodiment. The throttling gap forms a perimetrical boundary of a plenum cavity located below each of the pad assemblies 134 and above ground support. The inflatable inlet chambers 140 are each communicated with the plenum cavities by passageways 142 in the flexible diaphragm material adjacent the inner peripheral edge 138 thereof.

The mode of operation of the four pad assemblies 134, as to individual pad assemblies, corresponds to that previously discussed with reference to each of the pad assemblies 32, 34 of the previously described embodiment in FIGS. 1 through 12. The provision of four pad assemblies having a generally circular outline, as compared to the two pad assemblies with an oval shape, produces a more uniform uplifting air cushion effect on the platform 132, made possible by the greater number of pad assemblies. The operation of the individual pad assemblies otherwise corresponds to that of the pad assemblies previously discussed.

In this embodiment of the present invention, each of the pad assemblies 134 includes an inlet conduit 144 formed by the flexible diaphragm material between a valve control assembly 146 located centrally of pad 132 and each of the inflatable inlet chambers 140, as best seen in FIG. 13. The assembly 146 includes an upstanding sheet metal tubular member 148 that has an upper open end and a bottom open end located within a central opening 150 in the plate 132. The lower end of the tubular member 148 is bent continuously around its lower edge at 152 to secure the inlet member 148 in place on the plate 132.

A generally cylindrical valve housing 154 is located within the member 14 8. It includes a base cap 156 seated on a centrally located segment 158 of the diaphragm portion that defines an annular juncture 159 to each of the inlet conduits 144. The bottom cap 156 sealingly engages the lower edge of a plurality of radially inwardly directed walls 160, 162, 164, 1 66 located at evenly spaced points circumferentially around the inside peripheral surface of the valve housing 154. A first inlet passageway 168 is formed between walls 160, 162 and the inner peripheral surface of housing 154. A like inlet passageway 170 is formed between walls 162, 164. Like passageways 172 and 174 are defined between walls 164, 166 and 166, 160, respectively.

A conduit (not shown) like 82 in the first embodiment will direct pressurized air equally into each of the inlet passageways 168, 170, 172, 174. In this embodiment, each of these passageways communicate with a control passageway 176 defined by a radially inwardly directed lip 178 on the inner circumference of the valve housing 154 located at approximately the level of the load supporting plate 132 and being inclined upwardly as best seen in FIG. 16. The control passageway 176 is divided into four segments by the divider walls of the valve housing 154. Each of the control passageway segments is located in direct communication with one of the inlet conduits 144 in the diaphragm between the pad assemblies 134 and the air flow regulator assembly 1 46 through the annular juncture 159.

At the 'base of each of the divider walls is located a V-shaped radially inwardly directed transitional segment 180 of the housing 154 that diverts the flow from the divided segments ofthe control passageway 176 into the inlet conduits 144. Each of the transitional segments 180 are in alignment with a sealing gasket 182 having one face thereof in sealing engagement with the outer peripheral surface of the housing 154 adjacent its base and a radially outwardly located face in sealing engagement with a continuously formed side wall 184 that extends around the periphery of the central segment 158 of the diaphragm between the conduit forming branches 144 thereon. The sealing gaskets 182 separate the annular juncture 159 into four separate and distinct paths, each communicating one of the control passageway segments with an inlet conduit 144.

The bottom cap 156 includes a centrally located upstanding pedestal 186 thereon which has an inverted conical upper end surface 188 merging with a circular knife edge pivot line 190. The lower end of an elongated spring pin member 192 depending from a generally sperical ballshaped center segment 194 of a valving element 196 is centered within the surface 188 as best seen in FIG. 18. The element 196 controls flow from the inlet passageways to segments of the control passageway 176 in a proportional manner for stabilizing the device 130.

More particularly, the valving element 196 includes a plurality of radially outwardly directed fan-shaped vanes 198 each of which is located 'within one of the inlet passageways that communicate with a segment of the control passageway 176. More particularly, each of the vanes 198 each of which is located within one of the inlet ism with an adjacent divider wall of the valve housing.

154 and an arcuate outer peripheral edge 204 that, as best seen in FIG. 15, slightly overlaps the inner radial 10 edge of the lip 178 that defines the control passageway 176.

When the plate 132 is uniformly loaded, the vanes 198 are located in a horizontal disposition under the biasing or centering action of the spring 192. The valving element 196 is maintained centered by the spring 192 and seated on a spherical upper edge 206 of a tubular extension 208 that is integral with the divider walls 160, 162, 164, 166 at the base thereof, as best seen in FIGS. 16 and 18. The weight of the valving element 196 serves to maintain it on the seat 206, and a cross-shaped insert member 210' that fits into the housing 154 at the top thereof prevents upward movement of the valving element 196 within the housing 154.

The insert member 210 has a spherical surface 211 on its bottom immediately overlying the ball segment 194. It also includes outwardly directed arms 212 thereon, each with a tongue 214 on its outer edge that seats into a receiving groove formed in each of the adjacent inner edges of the divider walls of the housing 154 to maintain the insert 210 against turning movement.

The above-described unit is capable of supporting loads in the range of 600 to 1000 pounds when supplied with air pressure from sources of the type discussed in the first embodiment.

By virtue of the above-described arrangement of components in FIGS. 13 through 18, the air cushion device has an improved stability like that discussed with respect to the air cushion device 26 in the first embodiment. More particularly, the air flow regulator in this embodiment is capable of producing a proportional air flow into any one of the four pad assemblies 134 in accordance with the pressure level in the inlet chamber of the pad assembly 134 which varies depending upon the degree to which the support plate 132 is tilted with respect to underlying ground support in the vicinity of a particular one or more of the pad assemblies 134.

Thus, assuming that the plate 132 is tilted along a diagonal line from the upper right pad assembly 134 to the lower left pad assembly 134, as viewed in FIG. 13, so that the plate 132 is raised in the vicinity of the upper right pad assembly and moved toward the supporting ground in the lower left quadrant thereof, valving element 196 will be shifted from its centered position with the four spaced apart vanes 198 thereon located in a horizontal plane to the position shown in dotted lines in FIG. 16.

This results because the lower left pad assembly 134 is pressed toward the ground support and will have an increased pressure in its inlet chamber 140, and the pad assembly 134 that is raised from the ground support will have a reduced pressure in its inflatable inlet chamber. Thus, the vane element 198 in the inlet passageway 174 to the control passageway 176 will be acted upon by the greater pressure and raised upwardly to overcome the centering action of the spring 192. As seen in FIG. 16, the spring 192 is bowed between the spherically shaped center of the valving element 196 and the knife edge pivot point 190 on the pedestal 186.

Because there is a lesser pressure in the diametrically opposite pad assembly 134 in the upper right hand cor ner, as shown in FIG. 16, vane 198 in the passageway leading to the control passageway 176 is moved downwardly to almost completely close the segment of passageway 176 between passageway 170 and the inlet conduit 144 that leads to the upper right hand pad assembly.

Concurrently, the fan-shaped vane elements 198 in inlet passageways 168, 172 are tilted so that the edge 202 on the vane element in the passageway 168 will move closer to the lip 178 and the like edge 202 on the vane element 198 in passageway 172 will be raised upwardly of the lip 178.

The resultant effect is that air flow to the lower right pad assembly 134 will be increased by an amount equal to the decrease in air flow to the upper right hand pad assembly 134, as viewed in FIG. 13. The remaining pad assemblies 134 receive substantially the air flow occurring when the valving element 196 is in its horizontal centered disposition wherein the plate 132 is uniformly loaded. The corrective action on the plate 132, because of the changed air flow pattern, is identical to that discussed in the first embodiment.

In the arrangement of FIGS. 13 through 18, the valving element 196 can move from its horizontal disposition to an inclined position of the type discussed above, representing an unbalanced loading along a diagonal line. More complex loading patterns are compensated by a free universal movement of valving element 196 from the horizontal centered disposition. This particular disposition will depend upon the amount of pressure imbalance acting on one or a plurality of the vane elements 198 because of unbalanced loading on the platform 132.

As was the case in the first embodiment, by virtue of the above-described controlling action of the valve assembly 146, the pad assemblies 134 have a lesser tendency to ground into engagement with ground support, a phenomenon that necessarily destroys a desired air cushion action by the device 130. The resultant effect, therefore, is for greater stability of operation.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A ground proximate air cushion device comprising, a platform, flexible diaphragm means underlying said platform, said diaphragm means having inner and outer peripheral edges fixed to said platform to define plural annular depending convolutions each approaching contact with the ground at narrow annular zones between said peripheral edges, said platform and convolutions cooperating to form separate pressurizable inlet chambers, plural inlet conduits for directing super atmospheric air into said separate pressurizable inlet chambers, means for establishing and maintaining uplifting pressures on the underside of said diaphragm means and above ground surface at a point radially within the narrow annular zones defined by said convolutions and flowing with throttling through the said zones whereby the diaphragm means is subject to a first significant pressure differential between supplied air pressure and atmospheric pressure at a point radially outwardly of said annular zones and a second negligible pressure differential between supplied air pressure at opposite sides of said diaphragm means radially inwardly of said annular zones, said first pressure differential acting to induce a substantially circular crosssectional curvature in each of said convolutions from the outer margin thereof to said narrow annular zones, and said first and second pressure differentials coacting to cause the first pressure within said pressurizable inlet chambers to radially tension the portion of said convolution within said annular zones into a substantially truncated conical cross section, valve means for controlling air flow into said pressurizable chambers including a housing having an inlet and plural outlets, one of said outlets communicating with one of said inlet conduits and another of said plural outlets communicating with another of said inlet conduits, a movable valving element located within said housing between said inlet and said plural outlets, spring means for positioning said valving element in a centered position within said housing wherein said plurality of housing outlets directly fluidly communicate said housing inlet with said inlet conduits, said movable valving element being movable about a pivot point from its centered position, said valving element having surface regions on opposite sides of said pivot point directly acted on by pressure within each of said pressurizable inlet chambers, said platform and underlying diaphragm means coacting when an unbalanced loading tips said platform to produce a differential pressure between said pressurizable inlet chambers, said valving element shifting about said pivot point in response to such a differen- 12 tial pressure to move said surface regions with respect to said housing outlets to proportionally control flow through said outlets into said pressurizable chambers to produce greater air flow into the pressurizable chamber underlying the part of said platform tipped toward the underlying ground.

2. In a ground proximate air cushion device of the type having a load supporting platform with an underlying flexible diaphragm connected to the platform to define a plurality of separate pressurizable inlet chambers which are inflated to shape the flexible diaphragm into a plurality of pads each with a continuous perimetric convolution defining a throttling gap between the diaphragm and ground and wherein the throttling gap forms the perimeter of a plenum cavity between the underside of the diaphragm and ground through which air flows from the inlet chambers thence through the throttling gap to maintain an uplifting air pressure on the device, the improvement comprising a separate inlet conduit supplying air to each of the inlet chambers, a cylindrical valve housing having an inlet adapted to be connected to a source of pressure and a plurality of outlets, a divider wall in said housing separating said outlets from one another, a movable valving element located within said housing between said inlet and said plural outlets, spring means for positioning said valving element in a centered position within said housing wherein said plurality of housing outlets directly fluidly communicate said housing inlet with said inlet conduits, said movable valving element being movable about a pivot point from its centered position, said valving element having surface regions on opposite sides of said pivot point directly acted on by pressure within each of said inlet conduits, the platform and underlying diaphragm coacting when a unbalanced loading tips the platform to produce a differential pressure between said inlet conduits, said valving element shifting about said pivot point in response to such a differential pressure to move said surface regions with respect to said housing outlets to proportionally control flow through said outlets into said inlet conduits to produce greater air flow into the pressurizable inlet chamber underlying the part of said platform tipped toward the underlying ground.

3. In a gruond proximate air custhion device of the type having a load supporting platform with an underlying flexible diaphragm connected to the platform to define a plurality of separate pressurizable inlet chambers which are inflated to shape the flexible diaphragm into a plurality of pads each with a continuous perimetric convolution defining a throttling gap between the diaphragm and ground and wherein the throttling gap forms the perimeter of a plenum cavity between the underside of the diaphragm and ground through which air flows from the inlet chambers thence through the throttling gap to maintain an uplifting air pressure on the device, the improvement comprising a separate inlet conduit supplying air to each of the inlet chambers, a cylindrical valve housing having an inlet adapted to be connected to a source of pressure and a plurality of outlets, a divider wall in said housing separating said outlets from one another, means defining an opening in said wall, a movable valving element located in said divider wall opening extending throughout the height of said opening and blocking flow through said wall opening, means for supporting and centering said valve element with respect to said divider wall, said valving element having a first and second surface thereon located on opposite sides of said divider wall when said valving element is in its centered position, an arcuate outer peripheral surface segment on said valving element sildably sealingly engaging the inside surface of said housing during movement of said valving element within said housing, said housing outlets being in direct fluid communication with said housing inlet when said valving element is in its centered position, said valving element shifting in response to a pressure differential between said separate inlet conduits to cause said arcuate outer peripheral surface to move between said housing inlet and one of said housing outlets whereby more air flow passes into the inlet conduit having the greater pressure increase thence to the inlet chamber, plenum cavity and throttling gap of an associated diaphragm pad to produce a greater uplifting efiect thereon.

4. In a ground proximate air cushion device of the type having a load supporting platform with an underlying flexible diaphragm connected to the platform to define a plurality of separate pressurizable inlet chambers which are inflated to shape the flexible diaphragm into a plurality of pads each with a continuous perimetric convolution defining a throttling gap between the diaphragm and ground and wherein the throttling gap forms the perimeter of a plenum cavity between the underside of the diaphragm and ground through which air flows from the inlet chambers then through throttling gap to maintain an uplifting air pressure on the device, the improvement comprising a separate inlet conduit supplying air to each of the inlet chambers, a cylindrical valve housing having an inlet adapted to be connected to a source of pressure and a plurality of outlets, a divider walls in said housing separating said outlets from one another, a radially inwardly directed lip on said housing located between said housing inlet and said outlets, said lip extending between said walls to define a control opening to each of said outlets, a valving element having a spherically shaped center and a plurality of radially outwardly directed vanes, said valving element center being supported by said walls within said housing to located each of said vanes in pivotally movable overlying relationship wth one of said control openings, a spring connected between said valving element and said valve housing to maintain said valving element in a centered position where said vanes are disposed generally perpendicularly to the axis of said valve housing, said housing outlets being in direct fluid communication with said housing inlet when said valving element is in its centered position, said valving element shifting in response to a pressure differential between said separate inlet conduits to cause at least one of said vanes to tip toward one of said control openings to restrict flow therethrough while causing at least another of said vanes to tip away from another of said control openings to permit greater flow therethrough, said greater flow occurring to the inlet conduit having the greater pressure whereby more air flows through the inlet chamber, plenum cavity and throttling gap of the diaphragm pad associated with the greater pressure inlet conduit to produce more uplifting etfect thereon.

References Cited UNITED STATES PATENTS 3,245,487 4/ 1966 Mackie 124 3,251,432; 5/1966 Fischer et a1 180124 3,439,772 4/ 1969 Giraud 180-118 A. HARRY LEVY, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 330 Dated May 0 1970 Inventods) J. D. Llvesay It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 71, "sparate" should read --separate--. Column 2, line 43, "statetd" should read --stated. Column 5, line 2, "inherene" should read --inherent--:

Column 9, line 72, after "198" insert --includes side edges 200,202 in close spaced paralleland delete "each of which is located within one of the inlet".

Column 12, line '45, "gruond" should read -ground--; and "custhion" should read --cushion--.

Column 13, line 22 delete "a" second occurence; and line 30, "located" should read --locate.

SIGNED IND SEALED S'EP 25 1970 (S Anew Edward M. Fletcher. i mm 8 L- offiw mission of p J 

